Doctors could be one step closer to solving the mystery of why some children suffer recurring strep throat, a painful throat infection that if left untreated can lead to contagious skin sores, kidney problems, and rheumatic heart disease.

To test the theory, Jennifer Dan, MD, PhD, a coauthor of the study and an infectious disease specialist at UC San Diego Health, examined the surgically removed tonsils of 65 kids: 26 had their tonsils removed because of recurring episodes of tonsillitis, and 39 had them removed for an unrelated condition, such as sleep apnea.

Dr. Dan and colleagues found that children whose tonsils were removed due to recurrent infection had smaller germinal centers in their tonsils. Germinal centers live inside lymph nodes and help produce antibodies, the special proteins that fight off infection. Antibodies recognize and disable bacteria, and normally should be able to snuff out a strep infection before it strikes again.

“If these germinal centers are smaller, they might not be able to mount as good of an immune response,” Dan says.

The kids with recurrent tonsillitis were also more likely to have family members who had tonsillectomies, which suggests a genetic predisposition to a poor immune response.

Knowing exactly what causes recurring strep is also one of the keys to developing a vaccine. Matthew Brigger, MD, MPH, a study coauthor and the chief of otolaryngology at Rady Children’s Hospital in San Diego, says that not only would a vaccine address strep and other infections like tonsillitis, it would also reduce the need for surgeries like tonsillectomies.

“The surgery is very common and many children go through it, but it typically involves missing a week of school, there’s a risk of bleeding, and it’s one of the most painful surgeries we perform,” he says. “We do this surgery all the time, but we still don’t have a particularly good understanding of why some kids get it [tonsillectomies] and others don’t.”

This month, the American Academy of Otolaryngology updated its guidelines for performing tonsillectomies in children — something that hadn’t been done since 2011. Tonsillectomies used to be an extremely popular procedure, with more than 500,000 children under age 15 undergoing tonsillectomy in 2009. That number has dropped by about half, with the most recent National Health Statistics Report showing fewer than 300,000.

Mary Frances Musso, DO, a pediatric otolaryngologist at Texas Children’s Hospital, says the two main reasons children have tonsillectomies are for sleep apnea and recurring infections. With the updated guidelines, Musso can still recommend the surgery, but only if the child has at least seven infections in one year. And even with the surgery, some children will continue to get strep.

A vaccine may be a ways off, but Dr. Musso says the recent study offers new evidence for the causes of recurring strep, which would be a critical first step in developing a vaccine.

“This is the first time I’ve actually heard of someone mentioning the possibility of finding a Group A strep vaccine,” she says. “What they’re saying potentially could work. If they can develop a vaccine, it may be efficacious and lower the infection rate.”